Polycarbonate blends with high scratch resistance and ductility

Abstract

A blend of a first polycarbonate polymer comprising at least about 85% dimethyl bisphenol cyclohexane (DMBPC) units with a second polycarbonate polymer is disclosed. The blend has a combination of high scratch resistance and good ductility.

1 . A polycarbonate blend comprising:
 a first polycarbonate polymer comprising at least about 85% of dimethyl bisphenol cyclohexane (DMBPC) units of Formula (1):   
       
         
           
           
               
               
           
         
         a second polycarbonate polymer which differs from the first polycarbonate polymer; 
         wherein a molded sample of the polycarbonate blend has a scratch rating of F or harder according to ASTM D3363-92a and an impact value of at least 50 Joules according to ISO 6603. 
       
     
     
         2 . The polycarbonate blend of  claim 1 , wherein the first polycarbonate polymer has a melt volume flow rate of from about 4 to about 25 cm 3 /10 minutes. 
     
     
         3 . The polycarbonate blend of  claim 1 , wherein the second polycarbonate polymer has a melt volume flow rate of from about 5 to about 30 cm 3 /10 minutes. 
     
     
         4 . The polycarbonate blend of  claim 1 , wherein the weight ratio of the second polycarbonate polymer to first polycarbonate polymer is from about 10:90 to about 90:10. 
     
     
         5 . The polycarbonate blend of  claim 1 , wherein the weight ratio of the second polycarbonate polymer to first polycarbonate polymer is from about 40:60 to about 60:40. 
     
     
         6 . The polycarbonate blend of  claim 1 , wherein the second polycarbonate polymer comprises a monomer of Formula (II): 
       
         
           
           
               
               
           
         
       
       wherein R 1  through R 8  are each independently selected from hydrogen, halogen, nitro, cyano, C 1 -C 20  alkyl, C 4 -C 20  cycloalkyl, and C 6 -C 20  aryl; and A is selected from a bond, —O—, —S—, —SO 2 —, C 1 -C 12  alkyl, C 6 -C 20  aromatic, and C 6 -C 20  cycloaliphatic. 
     
     
         7 . The polycarbonate blend of  claim 1 , wherein the second polycarbonate polymer is of Formula (III): 
       
         
           
           
               
               
           
         
       
       wherein R 1  through R 8  are each independently selected from hydrogen, halogen, nitro, cyano, C 1 -C 20  alkyl, C 4 -C 20  cycloalkyl, and C 6 -C 20  aryl; A is selected from a bond, —O—, —S—, —SO 2 —, C 1 -C 12  alkyl, C 6 -C 20  aromatic, and C 6 -C 20  cycloaliphatic; and x is the degree of polymerization. 
     
     
         8 . The polycarbonate blend of  claim 1 , wherein the second polycarbonate polymer is a bisphenol-A homopolymer. 
     
     
         9 . The polycarbonate blend of  claim 1 , wherein the first polycarbonate polymer has a weight average molecular weight of from about 20,000 to about 30,000 g/mol. 
     
     
         10 . The polycarbonate blend of  claim 1 , wherein the second polycarbonate polymer has a weight average molecular weight of from about 20,000 to about 30,000 g/mol. 
     
     
         11 . The polycarbonate blend of  claim 1 , wherein the polycarbonate blend has an impact value of at least 100 Joules according to ISO 6603. 
     
     
         12 . A polycarbonate blend comprising:
 a dimethyl bisphenol cyclohexane (DMBPC) homopolymer having repeating units of Formula (1):   
       
         
           
           
               
               
           
         
         a bisphenol-A homopolymer; 
         wherein a molded sample of the polycarbonate blend has a scratch rating of F or harder according to ASTM D3363-92a and an impact value of at least 100 Joules according to ISO 6603. 
       
     
     
         13 . The polycarbonate blend of  claim 12 , wherein the DMBPC homopolymer has a melt volume flow rate of from about 4 to about 25 cm 3 /10 minutes. 
     
     
         14 . The polycarbonate blend of  claim 12 , wherein the bisphenol-A homopolymer has a melt volume flow rate of from about 5 to about 30 cm 3 /10 minutes. 
     
     
         15 . The polycarbonate blend of  claim 12 , wherein the weight ratio of the bisphenol-A homopolymer to DMBPC homopolymer is from about 40:60 to about 60:40. 
     
     
         16 . An article molded from a polycarbonate blend comprising:
 a first polycarbonate polymer including at least about 85% of dimethyl bisphenol cyclohexane (DMBPC) units of Formula (1):   
       
         
           
           
               
               
           
         
         a second polycarbonate polymer which differs from the first polycarbonate polymer; 
         wherein a molded sample of the polycarbonate blend has a scratch rating of F or harder according to ASTM D3363-92a and an impact value of at least 50 Joules according to ISO 6603. 
       
     
     
         17 . The article of  claim 16 , wherein the first polycarbonate polymer has a melt volume flow rate of from about 4 to about 25 cm 3 /10 minutes. 
     
     
         18 . The article of  claim 16 , wherein the second polycarbonate polymer has a melt volume flow rate of from about 5 to about 30 cm 3 /10 minutes. 
     
     
         19 . The article of  claim 16 , wherein the weight ratio of the second polycarbonate polymer to first polycarbonate polymer is from about 40:60 to about 60:40. 
     
     
         20 . The article of  claim 16 , wherein the second polycarbonate polymer is a bisphenol-A homopolymer. 
     
     
         21 . The article of  claim 16 , wherein the article is selected from the group consisting of a bezel, a keypad, a housing, and an optical display film.